The inventive device is preferably used for the approximation, mobilization, or fixation of tissue. As noted above, these terms are meant variously to include the specific movement of two regions of tissue towards each other, the movement of one or more selected tissue regions or areas, the maintenance of one or more selected tissue regions in a selected position, and the maintenance of a selected area of tissue against shape variation due to tissue “springiness.” Using our inventive device, a variety of approximation procedures may be achieved, variously from the movement of two tissue areas towards each other at a common wound margin to the maintenance of an area of tissue in a specific position during or after a surgical procedure, e.g. soft tissue in the middle and lower regions of the face or in the neck.
For instance, our inventive device allows healing of soft tissue due to its maintenance of tissue position. The surgically induced healing of soft tissue wounds involves two phases, the mechanical phase of wound closure followed by the biochemical phase which involves protein bridging and scarring. In the mechanical phase, the edges of soft tissue are held in contact by essentially two components: 1) The physical properties and device-tissue interactions of the materials holding the tissue edges in contact, e.g. sutures or staples; and 2) An early deposition of proteinaceous material that has adhesive characteristics, e.g. fibrin glue.
Only in the biochemical phase, which occurs after the mechanical phase, do tissue components replace the mechanical components adhering the displaced or wounded soft-tissue surfaces. During the biochemical phase, the inflammatory cascade generates signals which induce fibroblasts to migrate into the site or sites of wound healing and synthesize collagen fibers.
Collagen is the primary constituent of connective tissue and ultimately determines the pliability and tensile strength of the healing wound. Tensile strength is gradually recovered; 60% of ultimate wound strength is achieved after approximately 3 months. However, this process is successful only if the previous mechanical phase has proceeded normally.
The surgeon's goal is to optimize the strength and often the cosmetic appearance of a wound closure or tissue coaptation. For this to happen, tissue is mechanically approximated until the wound has healed enough to withstand stress without artificial support. Optimal healing requires the application of appropriate tissue tension on the closure to minimize or eliminate dead space but not create ischemia within the tissue. Both of these circumstances increase the risk of wound infection and wound dehiscence.
Although the biomaterial composition of sutures has progressed considerably, the sophistication of manual suture placement in wounds has advanced relatively little since the original use of fabrics several thousand years ago to tie wound edges together. The wide tolerance ranges for suture placement, tension, and configurations, both amongst different surgeons and for different implementations by the same surgeon, result in a significant component of sub-optimal technique. Yet, the technique used for wound closure forms the foundation for all subsequent events in the healing process. It is during this mechanical phase that tissue tension is high, edema and inflammation are intense, ischemia around the detached or wounded soft tissue is greatest, and that one can already observe the complication of optimal healing and fixation.
Soft tissue is well known for its inability to hold tension. Even when optimally placed, sutures gradually tear through soft tissue, producing gaps in wounds and possibly leading to the eventual failure or sub-optimization of wound healing. Furthermore, since sutures require the implementation of high levels of tension to counteract the forces acting to separate tissues, they may strangulate the blood supply of the tissues through which they are placed, thus inhibiting the delivery of nutrients and oxygen necessary for healing at and near the site of tissue fixation and repair.
There have been many attempts to construct wound closure devices that decrease closure time and improve cosmesis. U.S. Pat. Nos. 2,421,193 and 2,472,009 to Gardner; U.S. Pat. No. 4,430,998 to Harvey et al.; U.S. Pat. No. 4,535,772 to Sheehan; U.S. Pat. No. 4,865,026 to Barrett; U.S. Pat. No. 5,179,964 to Cook; and U.S. Pat. No. 5,531,760 to Alwafaie suggest such devices. However, these devices are not useful in surgical or deeper wounds. They only approximate the skin surface, joining skin edges variously through external approaches, using adhesives or nonabsorbable attachment points that penetrate tissue. The devices minimally improve the biomechanics of wound closure, and do not adequately approximate the deeper layers of the closure, i.e. fascia or dermis. Externally placed attachment points that puncture the skin lateral to the wound also interfere with long-term cosmesis and provide a possible conduit for infecting micro-organisms.
U.S. Pat. No. 5,176,692 to Wilk et al., discloses a device for hernia repair that utilizes mesh with pin-like projections to cover hernia defects. This device, however, is used in a laparoscopic hernia repair in conjunction with an inflatable balloon. Closure devices for deeper tissues are described in U.S. Pat. No. 4,610,250 to Green; U.S. Pat. No. 5,584,859 to Brozt et al.; and U.S. Pat. No. 4,259,959 to Walker. However, these devices either work in conjunction with sutures, are made of materials that do not suggest biodegradability, or are designed in such a way as not to impart uniform tension on the closure, increasing the risk of wound separation and failure of wound healing.
The present invention is a biodegradable tissue approximation device. The device includes a plurality of attachment points, e.g. tines, prongs, or other generally sharp or blunt parts, connected to one or more backings that can be manipulated to close wounds, join soft tissue or bone, approximate regions of soft tissue or create anastomoses. This multi-point tension distribution system device may be placed with minimal tissue trauma. Approximation from the internal aspect of the wound minimizes the potential for dead space in the closure, thus decreasing the risk of sub-optimal healing. Moreover, because the device is absorbed, a second procedure is not typically needed to remove the device.
Thus, the present invention improves the mechanical phase of healing and tissue approximation by facilitating the coaptation of tissues prior to initiation of the biochemical phase of biological healing. Placement of the device maximizes the chance for a good cosmetic result and is not heavily dependent on surgeon skill.
A variation of the present invention is well suited for inferior orbital rim, craniofacial, and maxillofacial reconstructive procedures.
Current orbital rim, craniofacial, and maxillofacial reconstructive procedures have a number of problems to overcome. The problems to be overcome arise from elevating the soft tissue or skin off the bone repair site. Elevating the soft tissue is generally necessary to access and repair the bone site. Typically, the fractured bones are set using a fracture fixation device such as a biocompatible or biodegradable plate which is attached to the underlying fractured bones using screws.
After the bone site is repaired, however, the soft tissue which was elevated must be re-anchored. Failure to re-anchor the soft tissue results in undesirable sagging or drooping.
Conventional techniques to reduce the sagging and drooping of soft tissue in these regions utilize sutures. Sutures are typically attached to screws or anchors or the bone itself via a drill hole. The soft tissue is then attached to the suture. This conventional technique is undesirable for the reasons set forth above in connection with the use of sutures.
The present invention overcomes the above noted problems by providing the inventive features herein described. In particular, the present invention provides one or more attachment points to hang soft tissue in the orbital, craniofacial, and maxillofacial regions to prevent sagging without the use of sutures. Furthermore, use of the present invention provides a one-step procedure for orbital fracture fixation and tissue approximation or fixation.
Other advantages of the present invention will become apparent from the following disclosure.